This application is based on Application No. 2000-259299, filed in Japan on Aug. 29, 2000, the contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a stator of a dynamo-electric machine and, more particularly, to a structure of a stator of an alternator driven by an internal combustion engine, such as a structure of a stator of an automotive alternator that can be mounted on a passenger car, a truck, or the like.
2. Description of the Related Art
FIG. 15 is a schematic perspective view showing conductor segments which are constituents of a stator winding in a stator of a conventional automotive alternator disclosed in, for example, Japanese Unexamined Patent Publication No. 11-164506. FIG. 16 is a simplified view showing coil-end groups in the conventional stator of the automotive alternator shown in FIG. 15, and FIG. 17 is a simplified view illustrating the layout of joint portions of the coil-end group in the conventional stator of the automotive alternator shown in FIG. 15.
Referring to FIG. 15, a first conductor segment 331 is formed by bending a copper constituent that is covered with an insulating film and has a rectangular cross section. The first conductor segment 331 is substantially formed into a U shape by connecting a pair of straight portions 331a and 331b at a turn portion 331c. A second conductor segment 332 is formed by bending a copper constituent that is covered with an insulating film and has a rectangular cross section. The second conductor segment 332 is also substantially formed into a U shape by connecting a pair of straight portions 332a and 332b at a turn portion 332c. 
In a conventional stator 100, a pair of the first conductor segment 331 and the second conductor segment 332 constructed as set forth above is inserted into a pair of slots of a stator iron core 101 from one end of a the stator iron core, the slots being spaced apart from each other by one magnetic pole pitch. Four straight portions 331a, 332a, 332b, and 331b are accommodated in each slot such that they are aligned in one row in the radial direction or the direction of slot depth. For the convenience of explanation, the positions of the straight portions aligned in each slot will be referred to as a first address, a second address, a third address, and a fourth address, the first address indicating the innermost position. As shown in FIG. 15, an end portion 331d of the first conductor segment 331 extending out from the first address of one slot to the other end of the stator iron core 101 is joined by welding to, for example, an end portion 332d of the second conductor segment 332 extending out from the second address of another slot to the other end of the stator iron core 101, the slot being spaced apart clockwise from the above slot by one magnetic pole pitch. Furthermore, an end portion 332e of the second conductor segment 332 extending out from the third address of one slot to the other end of the stator iron core 101 is joined by welding to, for example, an end portion 331e of the first conductor segment 331 extending out from the fourth address of another slot to the other end of the stator iron core 101, the slot being spaced apart clockwise from the above slot by one magnetic pole pitch. Thus, a lap-wound winding having four turns for each phase is formed. Furthermore, the lap-wound windings for three phases are ac-connected to make up a stator winding 102.
In the stator 100 configured as described above, a coil-end group 102a of the stator winding 102 at one end of the stator iron core 101 is constituted by the first conductor segments 331 and the second conductor segments 332 arranged in two layers in the circumferential direction such that the turn portions 331c of the first conductor segments 331 surround the turn portions 332c of the second conductor segments 332 in an axial direction, as shown in FIG. 16 and FIG. 17. A coil-end group 102b of the stator winding 102 at the other end of the stator iron core is constituted by a joint portion 334a of the end portions 331d and 332d and a joint portion 334b of the end portions 331e and 332e arranged adjacently in two layers in one row in the radial direction, being arrayed in two rows in the circumferential direction, the joint portions 334a and 334b being flush in the axial direction.
However, in the coil-end group 102b of the stator winding 102 of the conventional stator 100, the joint portions 334a and 334b are aligned in two layers adjacently in a single row in the radial direction, being arranged in two rows in the circumferential direction, and the heights of the joint portions 334a and 334b being the same in the axial direction. Hence, the radial interval between the joint portions 334a and 334b from which the insulating film has been lost due to welding is small, presenting a problem of proneness to short-circuiting. There has been another problem in that the joint portions 334a and 334b that are adjacent to each other in the radial direction and have the same height in the axial direction make it difficult to weld them, adversely affecting welding efficiency.
To solve the above problems, an improvement in which the joint portions 334a and 334b are arranged by shifting them in the circumferential direction has been proposed in, for example, Japanese Unexamined Patent Publication No. 2000-166150.
FIG. 18 is a schematic perspective view showing conductor segments of a stator winding in a stator of an improved conventional automotive alternator disclosed in, for example, Japanese Unexamined Patent Publication No. 2000-166150. FIG. 19 is a development partial side view, observed from an inner diameter side, of the stator of the conventional automotive alternator shown in FIG. 18. FIG. 20 is a simplified view illustrating the layout of joint portions in a coil-end group in the stator of the conventional automotive alternator shown in FIG. 18.
In an improved stator 100A, when welding end portions 331d, 332d, 331e, and 332e, the end portions of a first conductor segment 331 and a second conductor segment 332 extending out to the other end of a stator iron core 101 are tilted at different angles so as to cause joint portions 334a and 334b to be shifted in a circumferential direction by xe2x80x9cw,xe2x80x9d as shown in FIG. 18 and FIG. 19.
With this arrangement, a coil-end group 102b of the stator winding 102 at the other end of the stator iron core 101 is configured such that the joint portions 334a and 334b have the same axial height, and are shifted by xe2x80x9cwxe2x80x9d in the circumferential direction and arranged in two rows in the circumferential direction, as shown in FIG. 20.
The stator 100A shares the same construction as that of the stator 100 except that the joint portions 334a and 334b are shifted by xe2x80x9cwxe2x80x9d in the circumferential direction.
Another conventional stator structure employing first, second, and third conductor segments 331, 332, and 333 has been disclosed in, for example, Japanese Unexamined Patent Publication No. 2000-166150. In a stator 100B shown in FIGS. 21 and 22, a coil-end group 102a of a stator winding 102 is constituted by turn portions 331c, 332c, and 333c arranged in the circumferential direction in three layers in the axial direction. A coil-end group 101b is constituted by joint portions 334a, 334b, and 334c which share the same axial height and are arranged in three rows in the circumferential direction so that they are shifted in the circumferential direction by xe2x80x9cwxe2x80x9d.
In the stators 100A and 100B constructed as set forth above, the intervals between the joint portions are longer since the joint portions are shifted in the circumferential direction. This arrangement is expected to suppress the occurrence of short-circuiting between the joint portions that have lost an insulating film due to welding, and also to improve welding efficiency.
According to the stator 100 of the conventional automotive alternator 100, in the coil-end group 102b of the stator winding 102, the joint portions 334a and 334b share the same axial height and adjacently aligned in two layers in one row in the radial direction, being arrayed in two rows in the circumferential direction. This arrangement has been presenting a shortcoming in that the radial interval between the joint portions 334a and 334b that have lost the insulating film due to welding is short, frequently causing short-circuiting. There has been another shortcoming in that the joint portions 334a and 334b, which have the same height in the axial direction and are adjacent to each other in the radial direction, make it difficult to weld them, resulting in poor welding efficiency.
According to the stators 100A and 100B of the conventional automotive alternator, the joint portions 333a and 333b, or the joint portions 333a, 333b, and 333c, have the same height in the axial direction and are arranged in two or three rows in the circumferential direction so that they are shifted by xe2x80x9cwxe2x80x9d in the circumferential direction. With this arrangement, greater intervals can be allowed between the joint portions, so that the chance of short-circuiting between the joint portions can be minimized, permitting improved welding efficiency to be achieved.
However, in the stators 100, 100A, or 100B of the conventional automotive alternator stator, the coil-end group 102b is constructed by joint portions that have the same height in the axial direction and are arranged in two or three rows in the circumferential direction. This arrangement has been posing a problem in that the joint portions may be short-circuited from vibrations, leading to deterioration of insulating properties.
Furthermore, since the joint portions are configured to have the same height in the axial direction, as the number of rows in the circumferential direction increases, the joint portions are more prone to short-circuiting, and weldability deteriorates, making the construction disadvantageous in adding more rows.
Accordingly, the present invention has been made with a view toward solving the above problems, and it is an object of the present invention to provide a stator of a dynamo-electric machine in which joint portions of strands of wire are disposed adjacently to turn portions in a radial direction so as to eliminates the possibility of short-circuiting attributable to the joint portions, thereby allowing improved insulating properties to be achieved.
It is another object of the present invention to provide a stator of a dynamo-electric machine in which joint portions of strands of wire are disposed adjacently to turn portions or other joint portions with respect to the radial direction, and the axial height of the joint portions is made different from that of the turn portions adjoining the joint portions in the radial direction or other joint portions so as to eliminate the possibility of short-circuiting attributable to the joint portions, thereby allowing improved insulating properties and improved weldability to be achieved.
According to one aspect of the present invention, there is provided a stator of a dynamo-electric machine including a stator iron core provided with a plurality of slots arranged in a circumferential direction, and a stator winding constructed by joining a plurality of strands of wire installed in the slots spaced away by a predetermined number of the slots on an end surface of the stator iron core, wherein both coil-end groups of the stator winding are constructed by the joint portions interconnecting the strands of wire on the end surface of the stator iron core and turn portions of the strands of wire that extend out of one slot and enter another slot, the slots being spaced away from each other by a predetermined number of slots, on the end surface of the stator iron core, and on at least one coil-end group of the stator winding, the joint portions are disposed adjacently to the turn portions in the radial direction.
According to another aspect of the present invention, there is provided a stator of a dynamo-electric machine including a stator iron core provided with a plurality of slots arranged in a circumferential direction, and a stator winding constructed by joining a plurality of strands of wire installed in the slots spaced away by a predetermined number of the slots on an end surface of the stator iron core, wherein both coil-end groups of the stator winding are constructed by the joint portions interconnecting the strands of wire on the end surface of the stator iron core and turn portions of the strands of wire that extend out of one slot and enter the other slot, the slots being spaced apart from each other by a predetermined number of slots, on the end surface of the stator iron core, and on at least one coil-end group of the stator winding, the joint portions are disposed adjacently to the turn portions or other joint portions in the radial direction, and the axial height of the joint portions and the axial height of the turn portions adjacent to the joint portions in the radial direction or other joint portions are different.
In a preferred form, on at least one coil-end group of the stator winding, the joint portions, or the joint portions and the turn portions are stacked in three or more layers in one row in the radial direction.
In another preferred form, on at least one coil-end group of the stator winding, the turn portions are positioned adjacently to the joint portions at an inner radial side and an outer radial side of the joint portions and aligned in three layers in one row in the radial direction, and the axial height of the joint portions is greater than the axial height of the turn portions.
In yet another preferred form, an insulating resin is provided to cover the joint portions.
In a further preferred form, the insulating resin is provided between the joint portions adjoining in the radial direction and between the joint portions and the turn portions adjoining in the radial direction.
In another preferred form, varnish is applied to the coil-end groups.
In still another preferred from, on at least one coil-end group, the turn portion is located at an outermost radial position in the radial direction.
In another preferred from, the joint portion located at an outermost radial position is formed to have a lower axial height than the joint portion or the turn portion that is adjacent thereto in the radial direction.